Continuous integration with GitHub Actions

While we've already discussed GitHub Actions in detail in Chapter 10, Continuous Integration, and used it in the last chapter – Chapter 13, Understanding DevOps with GitOps – we will use GitHub Actions to build our code in the application repository. In this chapter, we will take a simple Flask application that returns The Secret is <secret_name> when we hit the home page. The secret is sourced from an environment variable called SECRET, and if it's not present, the application will return Secret not found. It will return a The page <page> does not exist. response for all other pages. We will deploy it in a Kubernetes environment (GKE). In the previous chapter, we created a GKE cluster using the push model of GitOps. We will leverage that in this chapter as well. We will use the GitHub flow for the application repository as we have an elementary example here, and as it is a microservice, it suits us well...